The entire event is being studied as part of "Operation Arrowtip," which investigates football-related crime, per The Guardian report.

Further comments were taken from a spokesman for Scotland Yard:

The Metropolitan police service is aware of incidents during the Arsenal v Tottenham Hotspur match on Saturday 4 January, where a number of objects were thrown from home and away sections of the crowd.

The MPS takes all such incidents seriously. Officers from Operation Arrowtip are investigating and are liaising with both clubs and the Football Association over these incidents.